Smart cards and tickets, and more particularly ISO format cards, have become extremely widespread in recent years. Above and beyond their use as credit cards, smart cards have become indispensable tools in many areas. This growth is largely due to the fact that, in addition to the traditional use of cards which make contact with the appropriate reader (e.g. bank and telephone cards), the new cards can be used without any physical contact with the reader.
The exchange of information between the contactless card or hybrid contact-contactless card and the associated reader is accomplished by remote electromagnetic coupling between an antenna integrated into the contactless card and a second antenna located in the reader. In order to create, store and process the information, the card is provided with a chip which is connected to the antenna. The antenna is generally located on a dielectric support made of plastic material. This ease of use has made the development of many other applications possible. For example, the development of the electronic wallet. In the transportation sector, smart cards have been developed as a means of paying highway tolls. At events, smart cards can be used by supporters as a season ticket for venues. For security applications, many companies have set up systems for staff identification based on ISO contactless smart cards.
The conventional contactless cards found on the market consist of several layers of plastic material, notably polyvinyl chloride (PVC). One of these layers constitutes the support for the antenna, and the others generally constitute the body of the card. The card's antenna is most commonly a copper wire or is chemically etched onto the card.
However, the production of such cards is relatively expensive. This is because the use of copper and etching processes are both expensive. Moreover, producing such an antenna on a PVC support necessarily entails using sophisticated—and therefore expensive—machinery.
Now, the development of contactless technology is dependent on a reduction in the manufacturing costs for such cards. One way of reducing production costs involves cheaper manufacturing methods for the antenna, notably by creating it using a screen-printing process with a conductive ink.
However, screen-printing on PVC is associated with a number of drawbacks. Furthermore, PVC exhibits poor thermomechanical properties. During the card body lamination process, material flow is significant and the antenna's shape factor is not maintained. Before lamination, when the conductive ink used to create the antenna is drying, the temperature is higher than that at which the plastic material becomes soft so there is deformation of the support which affects the antenna's electrical performance. This leads to antenna malfunction as electrical parameters (inductance and resistance) vary. Even more serious, it is not uncommon to experience antenna breakage in areas where strong sheer stresses are present. Moreover, it is impossible to replace the thermoplastic material with a thermosetting one since the latter is not amenable to hot lamination.
Another disadvantage is that, when the antenna is screen-printed onto PVC, connecting the chip to the antenna is much more difficult.